Considerable waste is involved with the manufacturing and use of asphalt roofing materials, such as shingles and rolled roofing membranes. For example, each new shingle has cut out tabs that are removed and discarded. Old shingle material removed from old buildings also provides a significant amount of roofing material waste.
Waste generated from roofing materials, such as asphalt shingles, presents a significant environmental concern because of the composition of the roofing material. Typical shingles are composed of a cellulose and/or fiberglass fiber mat, a saturating asphalt within the mat, an asphalt coating on the asphalt saturated mat and granules disposed on the coating. Such materials are difficult to break down and have typically required complex recycling processes.
One asphalt shingle recycling process is disclosed in U.S. Pat. No. 5,848,755 which is commonly owned by the assignee of the present invention and is fully incorporated herein by reference. The recycling system disclosed in the referenced patent application is capable of recycling asphalt roofing material and reducing granules, cellulose and fiberglass fibers and other particles in the asphalt roofing material to a fine mesh that can be maintained in suspension in liquid asphalt for later reuse.
Almost all roofing products that are used on sloped roofs use oxidized asphalt. Oxidized asphalt is asphalt that has been polymerized to increase its melt point. The oxidation/polymerization process increases the melt from approximately 100.degree. F. (Fahrenheit) to over 200.degree. F. In prior art asphalt roofing manufacturing processes, asphalt is oxidized by blowing high pressurized air into a tank of asphalt heated to approximately 400.degree. F. An exothermic reaction occurs, which polymerizes the asphalt. The lighter fractions of the asphalt are driven off as a byproduct of the reaction. This process, however, is very expensive because of the energy costs associated with heating the asphalt to the required polymerization temperature and the costs associated with pollution control devices and methods.
Nonetheless, for roofing material utilized on sloped roofs, the polymerization process to date, has been required to prevent asphalt from melting and running off of a sloped roof once the melt point of non-oxidized asphalt is exceeded.
Although the oxidization process does increase the melt point of asphalt, which is required for sloped roofing materials, the oxidation process does have it drawbacks. One significant drawback of the oxidation process is that oxidation reduces the life of asphalt.
Asphalt is made up of three chemical groups, aromatics, saturates and asphaltenes. As asphalt oxidizes, its chemical composition changes. The oxidation process changes the aromatics, which are light oils, into asphaltenes, which are fine particles. Thus, oxidation makes asphalt roofing materials brittle.
Further oxidation occurs as asphalt roofing materials naturally age on a roof. This makes the roofing material even more brittle, which reduces the adhesive properties of the material so that the granules can fall off. The roofing material is also more susceptible to cracking. Asphalt that is oxidized during the manufacturing process is pre-aged, because the aromatics are driven off, thus reducing the life span of roofing material before the material is even installed on a roof.
The disclosed recycled roofing material and method of manufacturing the same overcomes many of the drawbacks associated with current roofing materials by the addition of cellulose or glass fiber to the asphalt material, which provides a material with the desired elevated melt point without requiring the oxidation process.